On May 2, 2008, at 1:22 PM, Greg Smith wrote:
On Fri, 2 May 2008, Alexy Khrabrov wrote:
I have an UPDATE query updating a 100 million row table, and
allocate enough memory via shared_buffers=1500MB.
In addition to reducing that as you've been advised, you'll probably
need to increase checkpoint_segments significantly from the default
(3) in order to get good performance on an update that large.
Something like 30 would be a reasonable starting point.
I'd suggest doing those two things, seeing how things go, and
reporting back if you still think performance is unacceptable. We'd
need to know your PostgreSQL version in order to really target
future suggestions.
PostgreSQL 8.3.1, compiled from source on Mac OSX 10.5.2 (Leopard).
Saw the checkpoint_segments warning every ~20sec and increased it to
100 already. Will see what 512 MB buys me, but 128 MB was paging
miserably.
Cheers,
Alexy
